Just replaced the stock paste with Artic Silver 5 & temps are already 5-7 C lower under load & idle is about the same but obviously it has some cure time so may improve slightly. Nvidia have put way too much paste on the GPU & Heatsink it was at least 2mm thick and plenty to spare! Cleaned it all off with an Asaka TIM cleaner then applied a thin layer of AS5 with a proper spreader card
The real benefit of this is under heavy load the fans are less likely to spin up beyond the late 70% threshold where you can start to notice it so keeping the GPU cool will assist this plus also have an additional case fan which will suck cool air directly over the GTX480 from the case side so its all good